Studies on the Rheology and the Mechanical Properties of Thermoplastic Elastomer from Latex Product Waste and High Density Polyethylene

Latex waste products contain rubber hydrocarbon of very high quality, which is only lightly cross linked. Selected wastes such as thread waste and glove waste were modified into processable materials by a novel economic process and thermoplastic elastomers were prepared by blending these modified waste materials with high density polyethylene in various proportions. The mechanical properties as well as the rheological behaviour of these blends were evaluated and compared with those of the natural rubber-high density polyethylene blends.

Investigations on Structural response of Water Backed Perforated plates

The study envisaged herein contains the numerical investigations on Perforated Plate (PP) as well as numerical and experimental investigations on Perforated Plate with Lining (PPL) which has a variety of applications in underwater engineering especially related to defence applications. Finite element method has been adopted as the tool for analysis of PP and PPL. The commercial software ANSYS has been used for static and free vibration response evaluation, whereas ANSYS LS-DYNA has been used for shock analysis. SHELL63, SHELL93, SOLID45, SOLSH190, BEAM188 and FLUID30 finite elements available in the ANSYS library as well as SHELL193 and SOLID194 available in the ANSYS LS-DYNA library have been made use of. Unit cell of the PP and PPL which is a miniature of the original plate with 16 perforations have been used. Based upon the convergence characteristics, the utility of SHELL63 element for the analysis of PP and PPL, and the required mesh density are brought out. The effect of perforation, geometry and orientation of perforation, boundary conditions and lining plate are investigated for various configurations. Stress concentration and deflection factor are also studied. Based on these investigations, stadium geometry perforation with horizontal orientation is recommended for further analysis.Linear and nonlinear static analysis of PP and PPL subjected to unit normal pressure has been carried out besides the free vibration analysis. Shock analysis has also been carried out on these structural components. The analytical model measures 0.9m x 0.9m with stiffener of 0.3m interval. The influence of finite element, boundary conditions, and lining plate on linear static response has been estimated and presented. Comparison of behavior of PP and PPL in the nonlinear strain regime has been made using geometric nonlinear analysis. Free vibration analysis of the PP and PPL has been carried out ‘in vacuum’ condition and in water backed condition, and the influence of water backed condition and effect of perforation on natural frequency have been investigated.Based upon the studies on the vibration characteristics of NPP, PP and PPL in water backed condition and ‘in vacuum’ condition, the reduction in the natural frequency of the plate in immersed condition has been rightly brought out. The necessity to introduce the effect of water medium in the analysis of water backed underwater structure has been highlighted.Shock analysis of PP and PPL for three explosives viz., PEK, TNT and C4 has been carried out and deflection and stresses on plate as well as free field pressure have been estimated using ANSYS LS-DYNA. The effect of perforations and the effect of lining plate have been predicted. Experimental investigations of the measurement of free field pressure using PPL have been conducted in a shock tank. Free field pressure has been measured and has been validated with finite element analysis results. Besides, an experiment has been carried out on PPL, for the comparison of the static deflection predicted by finite element analysis.The distribution of the free field pressure and the estimation of differential pressure from experimentation and the provision for treating the differential pressure as the resistance, as a part of the design load for PPL, has been brought out.

New studies on the versatile roles of Polyaniline and its composites in polymer based optoelectronic and energy storage devices

From the early stages of the twentieth century, polyaniline (PANI), a well-known and extensively studied conducting polymer has captured the attention of scientific community owing to its interesting electrical and optical properties. Starting from its structural properties, to the currently pursued optical, electrical and electrochemical properties, extensive investigations on pure PANI and its composites are still much relevant to explore its potentialities to the maximum extent. The synthesis of highly crystalline PANI films with ordered structure and high electrical conductivity has not been pursued in depth yet. Recently, nanostructured PANI and the nanocomposites of PANI have attracted a great deal of research attention owing to the possibilities of applications in optical switching devices, optoelectronics and energy storage devices. The work presented in the thesis is centered around the realization of highly conducting and structurally ordered PANI and its composites for applications mainly in the areas of nonlinear optics and electrochemical energy storage. Out of the vast variety of application fields of PANI, these two areas are specifically selected for the present studies, because of the following observations. The non-linear optical properties and the energy storing properties of PANI depend quite sensitively on the extent of conjugation of the polymer structure, the type and concentration of the dopants added and the type and size of the nano particles selected for making the nanocomposites. The first phase of the work is devoted to the synthesis of highly ordered and conducting films of PANI doped with various dopants and the structural, morphological and electrical characterization followed by the synthesis of metal nanoparticles incorporated PANI samples and the detailed optical characterization in the linear and nonlinear regimes. The second phase of the work comprises the investigations on the prospects of PANI in realizing polymer based rechargeable lithium ion cells with the inherent structural flexibility of polymer systems and environmental safety and stability. Secondary battery systems have become an inevitable part of daily life. They can be found in most of the portable electronic gadgets and recently they have started powering automobiles, although the power generated is low. The efficient storage of electrical energy generated from solar cells is achieved by using suitable secondary battery systems. The development of rechargeable battery systems having excellent charge storage capacity, cyclability, environmental friendliness and flexibility has yet to be realized in practice. Rechargeable Li-ion cells employing cathode active materials like LiCoO2, LiMn2O4, LiFePO4 have got remarkable charge storage capacity with least charge leakage when not in use. However, material toxicity, chance of cell explosion and lack of effective cell recycling mechanism pose significant risk factors which are to be addressed seriously. These cells also lack flexibility in their design due to the structural characteristics of the electrode materials. Global research is directed towards identifying new class of electrode materials with less risk factors and better structural stability and flexibility. Polymer based electrode materials with inherent flexibility, stability and eco-friendliness can be a suitable choice. One of the prime drawbacks of polymer based cathode materials is the low electronic conductivity. Hence the real task with this class of materials is to get better electronic conductivity with good electrical storage capability. Electronic conductivity can be enhanced by using proper dopants. In the designing of rechargeable Li-ion cells with polymer based cathode active materials, the key issue is to identify the optimum lithiation of the polymer cathode which can ensure the highest electronic conductivity and specific charge capacity possible The development of conducting polymer based rechargeable Li-ion cells with high specific capacity and excellent cycling characteristics is a highly competitive area among research and development groups, worldwide. Polymer based rechargeable batteries are specifically attractive due to the environmentally benign nature and the possible constructional flexibility they offer. Among polymers having electrical transport properties suitable for rechargeable battery applications, polyaniline is the most favoured one due to its tunable electrical conducting properties and the availability of cost effective precursor materials for its synthesis. The performance of a battery depends significantly on the characteristics of its integral parts, the cathode, anode and the electrolyte, which in turn depend on the materials used. Many research groups are involved in developing new electrode and electrolyte materials to enhance the overall performance efficiency of the battery. Currently explored electrolytes for Li ion battery applications are in liquid or gel form, which makes well-defined sealing essential. The use of solid electrolytes eliminates the need for containment of liquid electrolytes, which will certainly simplify the cell design and improve the safety and durability. The other advantages of polymer electrolytes include dimensional stability, safety and the ability to prevent lithium dendrite formation. One of the ultimate aims of the present work is to realize all solid state, flexible and environment friendly Li-ion cells with high specific capacity and excellent cycling stability. Part of the present work is hence focused on identifying good polymer based solid electrolytes essential for realizing all solid state polymer based Li ion cells.The present work is an attempt to study the versatile roles of polyaniline in two different fields of technological applications like nonlinear optics and energy storage. Conducting form of doped PANI films with good extent of crystallinity have been realized using a level surface assisted casting method in addition to the generally employed technique of spin coating. Metal nanoparticles embedded PANI offers a rich source for nonlinear optical studies and hence gold and silver nanoparticles have been used for making the nanocomposites in bulk and thin film forms. These PANI nanocomposites are found to exhibit quite dominant third order optical non-linearity. The highlight of these studies is the observation of the interesting phenomenon of the switching between saturable absorption (SA) and reverse saturable absorption (RSA) in the films of Ag/PANI and Au/PANI nanocomposites, which offers prospects of applications in optical switching. The investigations on the energy storage prospects of PANI were carried out on Li enriched PANI which was used as the cathode active material for assembling rechargeable Li-ion cells. For Li enrichment or Li doping of PANI, n-Butyllithium (n-BuLi) in hexanes was used. The Li doping as well as the Li-ion cell assembling were carried out in an argon filled glove box. Coin cells were assembled with Li doped PANI with different doping concentrations, as the cathode, LiPF6 as the electrolyte and Li metal as the anode. These coin cells are found to show reasonably good specific capacity around 22mAh/g and excellent cycling stability and coulombic efficiency around 99%. To improve the specific capacity, composites of Li doped PANI with inorganic cathode active materials like LiFePO4 and LiMn2O4 were synthesized and coin cells were assembled as mentioned earlier to assess the electrochemical capability. The cells assembled using the composite cathodes are found to show significant enhancement in specific capacity to around 40mAh/g. One of the other interesting observations is the complete blocking of the adverse effects of Jahn-Teller distortion, when the composite cathode, PANI-LiMn2O4 is used for assembling the Li-ion cells. This distortion is generally observed, near room temperature, when LiMn2O4 is used as the cathode, which significantly reduces the cycling stability of the cells.

Apendicitis aguda perforada en adultos; aproximación a las inequidades sociales en salud, Bogotá 2012

La perforación del apéndice es una complicación temprana de la apendicitis aguda, demoras en el diagnóstico o tratamiento incrementan la tasa de perforación. Se desconoce si la perforación dl apéndice es un reflejo de inequidades sociales. Se pretendió determinar la asociación de la apendicitis aguda perforada en adultos y la equidad en acceso a salud. Estudio tipo cohorte retrospectivo documental, de historias clínicas de pacientes con apendicitis aguda; el análisis se realizó con Stata 11.1 y Epi-info. Los resultados se presentaron en tablas y figuras. Se incluyeron 540 casos (292 hombre y 248 mujeres), el grupo de edad que aporto más datos fue el de 18 a 49 años (391 pacientes); el tiempo medio de síntomas a consulta fue de 37,45 horas, y de 5,3 horas para el paso a cirugía desde el ingreso, fueron solicitadas 76 ecografías y 53 tomografías, 50 interconsultas a urología y 10 a ginecología hasta el diagnostico. El grupo de mayores de 49 años, el estrato socioeconómico tres y la tomografía fueron factores de riesgo independientes para perforación del apéndice. El análisis multivariado mostró asociación lineal entre el estrato socioeconómico y tiempo de síntomas al ingreso, tiempo para paso a cirugía, solicitud de ayudas diagnósticas e interconsultas, con buena significación estadística. La apendicitis aguda perforada en adultos, podría ser un indicador de inequidad en salud. Se requiere de estudios multi-céntricos, con mayor tiempo de evaluación y muestra para demostrar si el apéndice perforado es un trazador de inequidades en salud en Colombia.

Utilidad de la resonancia magnética en el diagnóstico de apendicitis aguda

Comparar el resultado de la resonancia magnética en el diagnóstico de apendicitis aguda con el patrón de oro (estudio histopatológico o seguimiento clínico del paciente) con el fin de establecer la utilidad de ésta como prueba diagnóstica y poder incluirla dentro del algoritmo de estudio de esta patología cuando hay sospecha clínica y un resultado negativo o dudoso de la ecografía abdominal

La incidencia del sistema de patentes estadounidense en la política de salud pública sudafricana 2000- 2012

El interés de este estudio de caso es explicar la incidencia del sistema de patentes estadounidense en la política de salud pública sudafricana del 2000 al 2012. Teniendo en cuenta los altos costos que este sistema impone en los precios de los medicamentos especialmente para tratar el VIH/SIDA y la malaria dos de los males que más aquejan a la población sudafricana. Se pretende explicar y establecer los cambios que ha implementado el gobierno sudafricano en su política de salud pública a través de la creación de una incipiente industria farmacéutica genérica que alivia en parte esta situación, pero que resulta insuficiente debido a su primordial interés de mantener relaciones cordiales con Estados Unidos antes que experimentar cualquier represalia como sucedió en India y Brasil.

Perforaciones duodenales posteriores a colangiopancreatografia retrograda endoscopica (CPRE) en el hospital universitario mayor - MEDERI

Las perforaciones duodenales posteriores a colangiopancreatografía retrógrada endoscópica (POST – CPRE) son un evento raro pero que genera aumento en la morbimortalidad del paciente expuesto a este método diagnóstico y terapéutico. El principal objetivo de este trabajo es describir una serie de casos haciendo énfasis en las características sociodemográficas y las relacionadas con el diagnóstico y el manejo.

Protocolo interno para la oferta de bienes y servicios y contratación de mano de obra de las comunidades

Los actores involucrados dentro de los proyectos de exploración y perforación de pozos petroleros son variados y tienen necesidades diferentes. El éxito y satisfactorio desarrollo de los proyectos va ligado en gran medida a temas de orden social entre los diferentes actores, que están definidos por regulaciones legislativas, de costumbres comerciales y culturales, políticas de responsabilidad social y procedimientos internos de las compañías involucradas (Operadoras, Prestadoras de Servicios Petroleros, Contratistas y Subcontratistas) Después de analizar la situación de la industria, los resultados de Halliburton SRL Sucursal Colombia, los problemas y sobrecostos generados por temas de orden social. Se identificó que la mayoría de ellos eran causados por falta de comunicación, desconocimiento de elementos clave de las políticas de responsabilidad social de los clientes, desconocimiento de la importancia de la responsabilidad social como práctica y desconocimiento de la normatividad legal vigente aplicable a la industria y a la actividad que desarrolla la compañía. De las necesidades y problemáticas descritas anteriormente surge la idea de crear una herramienta que permita llenar los vacíos de información identificados, alinear a las partes involucradas dentro del proceso y ser una guía para el inicio, desarrollo y cierre de proyectos de exploración y perforación de pozos petroleros que desarrolle Halliburton con sus clientes.

El Proyecto Globe en la Regi??n de Murcia

Las actividades proyectadas se realizan en salidas escolares a distintos enclaves de la provincia de Murcia y participan tres institutos vinculados al programa internacional 'Glove' a trav??s de sus profesores de ciencias de la naturaleza y f??sica-qu??mica. El objetivo de esta actividad coincide con el del proyecto internacional del que participan m??s de 70 naciones y es impulsar educativamente el conocimiento del medio ambiente analizando todos los factores que inciden en su equilibrio, cuya observaci??n y estudio permite corregir o prevenir aquellos aspectos que son fundamentales para la vida en el planeta y de los seres que en ??l habitan. El proceso seguido est?? formalmente establecido en el proyecto internacional y se basa en la toma de mediciones ambientales a trav??s de protocolos adaptados al nivel de los alumnos participantes: protocolo atm??sf??rico, hidrol??gico, GPS y cobertura terrestre y fenol??gico. Entre los resultados hay que destacar el manejo correcto del instrumental necesario en los protocolos y el empleo de los conceptos ambientales b??sicos para elaborar una explicaci??n cient??fica de los principales problemas y la interpretaci??n y elaboraci??n de gr??ficas de los datos obtenidos en el estudio medioambiental. Se particip?? como grupo de trabajo en el I Congreso Nacional de Medio Ambiente celebrado en Santander, elaborando una ponencia titulada Murcia, una regi??n en busca del agua que se ha publicado junto a la documentaci??n preparatoria. Se ha evaluado tanto a los alumnos como el desarrollo del proyecto..

The effect of cues on young children’s abilities to discriminate among thoughts, feelings and behaviours

Objective: To determine if cues help young children discriminate among thoughts, feelings and behaviours. Participants: Ninety-six children aged 4–7 years from three schools in Norwich, UK. Design: Within each age band (4, 5, 6, 7), children were randomised to the cue or the no cue condition on a stratified basis ensuring that equal numbers of boys and girls from each school were in each of the eight cells (cue condition×age). Cues were glove puppets and post boxes. The effect of IQ was controlled. Measures: A discrimination task, in which children were asked to identify a thought, a feeling and a behaviour from each of six brief stories, and a brief IQ assessment were administered to children individually. Results: There was a significant effect of age and cue condition on performance; older children and those who were presented with the cue performed better. There were no gender differences and no interaction between cue condition and age. Conclusion: Many young children discriminated among thoughts, feelings and behaviours suggesting that they may be able to engage in this aspect of cognitive behaviour therapy. Simple cues (puppets and posting boxes) improved children’s performance and these may be useful therapeutic tools with young children.

Immunohistochemical, tomographic and histological study on onlay iliac grafts remodeling

The information concerning the molecular events taking place in onlay bone grafts are still incipient. The objective of the present study is to correlate the effects of perforation of resident bone bed on (1) the timing of onlay autogenous graft revascularization; (2) the maintenance of volume/density of the graft (assessed through tomography); and (3) the occurrence of bone remodeling proteins (using immunohistochemistry technique) delivered in the graft. Thirty-six New Zealand White rabbits were subjected to iliac crest onlay bone grafting on both sides of the mandible. The bone bed was drill-perforated on one side aiming at accelerating revascularization, whereas on the other side it was kept intact. After grafts fixation and flaps suture all animals were submitted to tomography on both mandible sites. Six animals were sacrificed, respectively, at 3, 5, 7, 10, 20 and 60 days after surgery. A second tomography was taken just before sacrifice. Histological slides were prepared from each grafted site for both immunohistochemistry analysis [osteopontin, osteocalcin, type I collagen and vascular endothelial growth factor (VEGF) anti-bodies] and histometric analysis. The values on bone volume measured on tomography showed no statistic significance (P >= 0.05) between perforated and intact sites. Grafts placed on perforated beds showed higher bone density values compared with non-perforated ones at 3 days (P <= 0.05). This correlation was inverted at 60 days postoperatively. The findings from VEGF labeling revealed a tendency for earlier revascularization in the perforated group. The early revascularization of bone grafts accelerated the bone remodeling process (osteocalcin, type I collagen and osteopontin) that led to an increased bone deposition at 10 days. The extended osteoblast differentiation process at intermediate stages in the perforated group cooperated for a denser bone at 60 days.

Morphometric analysis of tracheary elements in four Portulaca species

This paper deals with the morphological features of the tracheary elements of the vegetative organs in four Portulaca species (Portulaca hirsutissima Camb., P. halimoides L., P. wedermannii Poelln. and P. mucronata Link.) occurring in Southeast and Northeast Brazil. The vessel elements are small (< 25 mu m) and with simple perforation plate. The pattern of wall thickening varied from bordered pitting (in roots) to scalariform and helicoidal (stem and leaves). Statistical methods show variation in vessel-element diameter in different vegetative organs; wider elements were observed in roots. Tracheids occurring in leaves of P. hirsutissima and P. wedermannii, have morphological features that are similar to terminal tracheids or tracheoid idiolasts frequently associated with xerophytes. The paedomorphic features (juvenlism) observed here may be related, in part, to aspects of water transport and storage as described in Cactaceae.

Placement of Kuhlmanniodendron Fiaschi & Groppo in Lindackerieae (Achariaceae, Malpighiales) confirmed by analyses of rbcL sequences, with notes on pollen morphology and wood anatomy

The phylogenetic placement of Kuhlmanniodendron Fiaschi & Groppo (Achariaceae) within Malpighiales was investigated with rbcL sequence data. This genus was recently created to accommodate Carpotroche apterocarpa Kuhlm., a poorly known species from the rainforests of Espirito Santo, Brazil. One rbcL sequence was obtained from Kuhlmanniodendron and analyzed with 73 additional sequences from Malpighiales, and 8 from two closer orders, Oxalidales and Celastrales, all of which were available at Genbank. Phylogenetic analyses were carried out with maximum parsimony and Bayesian inference; bootstrap analyses were used in maximum parsimony to evaluate branch support. The results confirmed the placement of Kuhlmanniodendron together with Camptostylus, Lindackeria, Xylotheca, and Caloncoba in a strongly supported clade (posterior probability = 0.99) that corresponds with the tribe Lindackerieae of Achariaceae (Malpighiales). Kuhlmanniodendron also does not appear to be closely related to Oncoba (Salicaceae), an African genus with similar floral and fruit morphology that has been traditionally placed among cyanogenic Flacourtiaceae (now Achariaceae). A picrosodic paper test was performed in herbarium dry leaves, and the presence of cyanogenic glycosides, a class of compounds usually found in Achariaceae, was detected. Pollen morphology and wood anatomy of Kuhlmanniodendron were also investigated, but both pollen (3-colporate and microreticulate) and wood, with solitary to multiple vessels, scalariform perforation plates and other features, do not seem to be useful to distinguish this genus from other members of the Achariaceae and are rather common among the eudicotyledons as a whole. However, perforated ray cells with scalariform plates, an uncommon wood character, present in Kuhlmanniodendron are similar to those found in Kiggelaria africana (Pangieae, Achariaceae), but the occurrence of such cells is not mapped among the angiosperms, and it is not clear how homoplastic this character could be.

INCREASED WATER STORAGE CAPACITY IN CACTUS WOOD: A STUDY IN THE TRIBE CEREEAE (CACTOIDEAE, CACTACEAE)

Secondary xylem of fibrous cactus wood is characterized by short narrow vessel elements with both simple perforation plates and large intervessel pits, libriform septate fibers, and large rays. These are present in basal cactus taxa, as well as in many other groups of the family. In Cactoideae, the most diversified and most derived subfamily, there are remarkable variations found in the secondary xylem, with the more highly derived taxa containing the greatest water storage capacity. Unlignified parenchyma is one specialization found in the fibrous wood of cacti. We observed this tissue in the secondary xylem at the base of the sterns of several Brazilian endemic species of Arrojadoa, Melocactus, and Stephanocereus, all members of the tribe Cereeae. In Arrojadoa and Melocactus the unlignified parenchyma occurs in lines and bands amongst the axial and radial xylem elements, while in Stephanocereus it is mainly restricted to the rays and does not form bands. We address the adaptive importance of the unlignified parenchyma in the fibrous wood in tribe Cereeae and the family Cactaceae as a whole.

Melting Regime of the Anionic Phospholipid DMPG: New Lamellar Phase and Porous Bilayer Model

Aqueous dispersions of the anionic phospholipid dimyristoyl phosphatidylglycerol (DMPG) at pH above the apparent pK of DMPG and concentrations in the interval 70-300 mM have been investigated by small (SAXS) and wide-angle X-ray scattering, differential scanning calorimetry, and polarized optical microscopy. The order. disorder transition of the hydrocarbon chains occurs along an interval of about 10 degrees C (between T(m)(on) similar to 20 degrees C and T(m)(off) similar to 30 degrees C). Such melting regime was previously characterized at lower concentrations, up to 70 mM DMPG, when sample transparency was correlated with the presence of pores across the bilayer. At higher concentrations considered here, the melting regime persists but is not transparent. Defined SAXS peaks appear and a new lamellar phase L(p) with pores is proposed to exist above 70 mM DMPG, starting at similar to 23 degrees C (similar to 3 degrees C above T(m)(on)) and losing correlation after T(m)(off). A new model for describing the X-ray scattering of bilayers with pores, presented here, is able to explain the broad band attributed to in-plane correlation between pores. The majority of cell membranes have a net negative charge, and the opening of pores across the membrane tuned by ionic strength, temperature, and lipid composition is likely to have biological relevance.